• 구강회복응용과학지
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• 제19권1호
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• pp.17-25
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• 2003

Treatment with implants of single tooth missing cases is both functional and esthetic. Although the success rate of single-tooth implant treatments is increasing, sometimes it makes some problems. Problems with single-tooth implant treatments include soft tissue complications, abutment screw fracture, and most commonly, abutment screw loosening, and these involve the instability of the dental implant-superstructure interface. This study investigated and compared dental implant screw joint micromotion of various implant system with external connection or internal connection when tested under simulated clinical loading, Six groups (N=5) were assessed: (1) Branemark AurAdapt (Nobel Biocare, Goteborg, Sweden), (2) Branemark EsthetiCone (Nobel Biocare, Goteborg, Sweden), (3) Neoplant Conical (Neobiotec, Korea), (4) Neoplant UCLA (Neobiotec, Korea), (5) Neoplant 5.5mm Solid (Neobiotec, Korea), and (6) ITI SynOcta (Institute Straumann, Waldenburg, Switzerland). Six identical frameworks were fabricated. Abutment screws were tightened to 32-35 Ncm and occlusal screw were tightened to 15-20 Ncm with an electronic torque controller. A mechanical testing machine applied a compressive cyclic load of 20kg at 10Hz to a contact point on each implant crown. Strain gauge recorded the micromotion of the screw joint interface once a second. Data were selected at 1, 500, 5,000, 10,000, 20,000, 30,000, 40,000 and 50,000 cycle and 2-way ANOVA test was performed to assess the statistical significance. The results of this study were as follows; The micromotion of the implant-superstructure in the interface increased gradually through 50,000 cycles for all implant systems. In the case of the micromotion according to cycle increase, Neoplant Conical and Neoplant UCLA system exhibited significantly increasing micromotion at the implant-superstructure interface (p<0.05), but others not significant. In the case of the micromotion of the implant-superstructure interface at 50,000 cycle, the largest micromotion were recorded in the Branemark EsthetiCone, sequently followed by Neoplant Conical, Neoplant UCLA, Branemark AurAdapt, ITI SynOcta and Neplant Solid. Internal connection system showed smaller micromotion than external connection system. Specially, Neoplant Solid with internal connection system exhibited significantly smaller micromotion than other implant systems except ITI SynOcta with same internal connection system (p<0.05). In the case of external connection, Branemark EsthetiCone and Neoplant Conical system with abutment showed significantly larger micromotion than Branemark AurAdapt without abutment (p<0.05).

• 대한치과기공학회지
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• 제39권2호
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• pp.75-82
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• 2017

Purpose: This study provided the basic data for selection the zirconia block and CAM by means of marginal fitness observations, flexural strength test and hardness test. Methods: Three dental zirconia blocks(ABCera, NaturaZ, ST98) and two dental milling machines(CAD/CAM MS, DWX-50) were used in this study. Metal abutment(diameter 10 mm, height 5 mm, inclined angle $3^{\circ}$ taper, 1 mm chamfer margin) was fabricated by Ti customized abutment, and then zirconia copings were fabricated for each ten specimens. Silicone replica technique was used to observe the marginal fitness of cross-sections with a stereomicroscope at ${\times}50$ magnification. The dental zirconia blocks was cut into 10 pieces each having a size of $25mm{\times}5mm{\times}1mm$, and fabricated according to the manufacturer's instructions, and flexural strength was measured using a universal testing machine. For hardness test, a micro Vickers hardness tester was used as it was in the flexural strength test. Statistical analysis was performed by one way ANOVA and post-test was performed by Scheffe test. Results: For marginal fitness of bucco-lingual axial, ZU group($59.7{\pm}10.3{\mu}m$) was the lowest, followed by RA, ZA, ZD, RD, RU. For marginal fitness of mesio-distal axial, ZU group($59.3{\pm}10.2{\mu}m$) was the lowest, followed by RA, ZA, RD, ZD, RU. One-way ANOVA showed statistically significant difference between groups(p<0.05). For flexural strength, ABCera block($718.0{\pm}57.2MPa$) was the highest, followed by NaturaZ, ST98. For hardness, ABCera block($1550.3{\pm}19.8Hv$) was the highest, followed by ST98, NaturaZ. There was no significant difference in flexural strength and hardness between blocks(p>0.05). Conclusion: Based on the results of this study, the type of dental zirconia block did influence the marginal fitness, and all dental zirconia blocks are expected to be suitable for clinical application. The highest flexural strength and hardness were ABCera block, and no statistically significant difference was observed.

• 대한치과보철학회지
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• 제38권2호
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• pp.226-241
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• 2000

Recently a new generation of crown and bridge veneering resins containing submicron glass fillers was introduced. These ultrasmall particle hybrid composite materials distinguish themselves, compared with conventional microfill crown and bridge resins, through improved mechanical properties. It is claimed that these composites are suitable for metal free crowns and even bridges using fiber reinforcement. The purpose of this study was to evaluate the effect of thermal cycling on the tensile strength of the following veneering composites: Artglass(Heraeus Kulzer Co., Wehrheim, Germany), Estonia(Kuraray Co.. Japan), Sculpture(Jeneric Pentron Co., Wallingford, U.S.A.), and Targis(Ivoclar Co., Schaan Liechenstein). According to manufacturer's instructions, rectangular tensile test specimens measuring $1.5{\times}2.0{\times}4.5mm$ were made using a teflon mold. Whole specimens were divided into two groups. One group was dried in a desiccator at $25^{\circ}C$ for 10 days, and another group was subjected to thermal cycling($10,000{\times}$) in water($5/55^{\circ}C$). All test specimens were placed in a universal testing machine and loaded until fracture with a crosshead speed of 0.5mm/min. Weibull analysis and Tukey's test were used to analyze the data. The fracture surfaces of specimens were observed in SEM and the aliphatic C=C absorbance peak of Estenia and Targis resin was analyzed using Fourier transform infrared(FTIR) spectroscopy. Within the limitations imposed in this study, the following conclusions can be drawn: 1. Both in drying condition and thermal cycling condition, the highest tensile strength was observed in Estenia testing group(p<0.05). 2. The strength data were at to single-mode Weibull distribution, and the Weibull modulus of all veneering composite resin specimens increased after thermal cycling treatment. 3. After thermal cycling test, the highest tensile strength was observed in the Estenia group, and the lowest value was observed in the Targis group. The tensile strength values showed the significant differences between each group(p<0.05) 4. The aliphatic C=C absorbance peak of Estonia and Targis resin was decreased after light curing, and there was no distinct change after thermal cycling.

• 대한치과보철학회지
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• 제44권5호
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• pp.642-653
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• 2006

Purpose : The purpose of this study was to investigate the effect of the output energy(voltage) of laser welding on the strength and properties of joint of cast titanium(CP Gr II) and titanium alloy(Ti-6Al-4V). Material and method : Cast titanium and its alloy rods(ISO6871) were prepared and perpendicularly cut at the center of the rod. After the cut halves were fixed in a jig, and the joints welded with a laser-welding machine at several levels of output voltage of $200V{\sim}280V$. Uncut specimens served as the non-welded control specimens The pulse duration and pulse spot size employed in this study were 10ms and 1.0mm respectively. Tensile testing was conducted at a crosshead speed of 0.5mm/min. The ultimate tensile strength(MPa) was recorded, and the data (n=6) were statistically analyzed by one-way analysis of variance(ANOVA) and Scheffe's test at ${\alpha}$=0.05. The fracture surface of specimens investigated by scanning electron microscope (SEM). Vickers microhardness was measured under 500g load of 15seconds with the optimal condition of output voltage 280V. Results : The results of this study were obtained as follows, 1. When the pulse duration and spot size were fixed at 10ms and 1.0mm respectively, increasing the output energy(voltage) increased UTS values and penetration depth of laser welded to titanium and titanium alloy. 2. For the commercial titanium grade II, ultimate tensile strength(665.3MPa) of the specimens laser-welded at voltage of 280V were not statistically(p>0.05) different from the non-welded control specimens (680.2MPa). 3. For the titanium alloy(Ti-6Al-4V), ultimate tensile strength(988.3MPa) of the specimens laser-welded at voltage of 280V were statistically(p<0.05) different from the non-welded control specimens (665.0MPa). 4. The commercial titanium grade II and titanium alloy(Ti-6Al-4V) were Vickers microhardness values were increased in the fusion zone and there were no significant differences in base metal, heat-affected zone.

• 대한치과보철학회지
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• 제49권1호
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• pp.49-56
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• 2011

연구 목적: 최근 지르코니아가 전부도재관의 코어로 많이 사용되고 있다. 지르코니아와 레진 시멘트의 결합 강도를 높이기 위한 기계적, 화학적인 표면 처리 방법들이 연구되고 있다. 이 연구에서 여러 표면 처리 방법에 따른 지르코니아와 레진 시멘트의 전단결합강도를 알아보고자 한다. 연구 재료 및 방법: 80개의 지르코니아 (Lava, 3M ESPE, St. Paul, MN, USA) 시편과 80개의 지르코니아/알루미나 복합체 (Zirace, Acucera Co Inc, Korea) 시편을 디스크형태로 제작하여 에폭시레진에 매립하였다. 이들을 각각 4개의 군으로 나누어 $50\;{\mu}m$ $Al_2O_3$ sandblasting, $110\;{\mu}m$ $Al_2O_3$ sandblasting, $50\;{\mu}m$ $Al_2O_3$ sandblasting과 프라이머 (Z-PRIME Plus, Bisco Inc, Schaumburg, IL, USA) 사용, $110\;{\mu}m$ $Al_2O_3$ sandblasting과 프라이머 (Z-PRIME Plus) 사용 군으로 나누었다. 표면 처리한 지르코니아 표면에 2가지 레진 시멘 (Calibra, Panavia F)으로 접착하였다. 그 후 증류수 ($37^{\circ}C$)에 24시간 보관 후 전단 결합 강도 실험을 시행하였고, SEM을 사용하여 표면 처리한 표면과 전단강도 실험 후 파절양상을 관찰하였다. 결과: ANOVA분석에 따르면, 두 가지 종류의 시편 모두에서, 프라이머 (Z-PRIME Plus)를 사용하여 표면 처리한 군들이 전단 결합 강도가 높았다 (P < .05). 결론: 기계적 결합 강도와 함께 새로운 프라이머를 사용하는 것이 지르코니아와 레진 시멘트의 접착 강도를 증가시킨다.

• 대한소아치과학회지
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• 제28권1호
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• pp.146-153
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• 2001

콤포짓트 레진의 다양한 성분은 기계적 성질에 많은 영향을 미치고, 수복물 주위의 환경 또한 재료의 성질에 많은 영향을 줄 수 있다. 구강 내에서 수복된 콤포짓트 레진은 항상 수분에 노출되어 있고, 콤포짓트 레진의 매트릭스는 수분을 흡수할 수 있으므로, 그 결과 콤포짓트 레진은 팽창하게 된다. 또한 콤포짓트 레진의 수분 흡수가 표면강도와 마모저항의 저하와 관계된 다고 알려져 있는바 저자는 치과용 콤포짓트 레진의 수분 흡수에 따른 압축강도와 굴곡강도의 변화에 관하여 알아보고자 하였다. 재료는 1군을 Z-100(3M, U.S.A.), 2군을 Spectrum(Dentsply, U.S.A.), 3군을 Clearfil AP-X(Kuraray, Japan), 4군을 Pyramid(Bisco, U.S.A), 5군을 Heliomolar(Vivadent, Germany)로 나누어 7일, 30일, 60일, 120일간 증류수에 넣어 $37^{\circ}C$에서 보관한 후 Instron 6022(Instron, U.K.)를 이용하여 압축강도와 굴곡강도를 측정하여 다음과 같은 결과를 얻었다. 1. 7일, 30일, 60일, 120일로 기간이 증가함에 따라 모든 군에서 압축강도가 감소하였다(p<0.05). 2. 7일, 30일, 60일, 120일로 기간이 증가함에 따라 모든 군에서 굴곡강도가 감소하였다(p<0.05). 3. Hybrid type인 1, 2, 3군에 비해 matrix 비율이 높은 microfine type인 5군이 강도가 낮았다.

• Tuberculosis and Respiratory Diseases
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• 제40권1호
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• pp.29-34
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• 1993

연구배경 : Ikeda에 의해 임상에 도입된 굴곡성 기관지경은 각종 폐 질환의 진단과 치료에 광범위하게 이용되고 있으며 시술 증례도 증가하고 있으나 외국에서는 결핵균, 비결핵항산균 및 여러 세균들에 의한 기관지경의 교차오염예가 다수 보고되고 있으므로 기관지경의 세척과 소독방법에 대해 주의를 기울여야 한다. 방법 : 1991년 11월부터 1992년 5월 까지 기관지내시경을 시행한 예중에서 기관지세척액에서 비결핵항산균이 배양된 예들을 분석하고 본원에서 화학살균제로 사용하고 있는 2% alkaline glutaraldehyde의 살균작용을 평가하기 위하여 실험실내에서 2% alkaline glutaraldehyde와 비결핵항산균 및 세균을 접촉시킨후 균의 사멸 여부를 알아 보았다. 결과 : 2% glutaraldehyde 소독제 용액에 비결핵항산균은 2% glutaraldehyde 1:1 용액으로 30분간 접촉한 후 균이 자라지 않았으며 그 밖의 세균들은 접촉 바로 후에 자라지 않았다. 위발생 인지후 철저한 기계적 세척과 함께 세척기내에서 30분이상 2% glutaraldehyde에 담가둔 이후로는 위양성이 발생하지 않았다. 결론 : 기관지경 사용후 기계적 세척을 철저히 하는 것이 중요하며 2% glutaraldehyde 용액으로 소독시 비결핵항산균의 소멸을 기대하려면 적어도 30분 이상 접촉이 필요할 것으로 생각된다. 또한 감염조절 방법을 엄격하게 적용한다 하더라도 오염을 완전히 배제할 수 없으므로, 일반적으로 비병원균으로 알려진 균들이 비통상적으로 갑자가 높은율로 검출되면 위발생을 생각하여야 한다.

• 한국식품저장유통학회지
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• 제13권4호
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• pp.438-444
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• 2006

감자와 고구마의 박피 방법별 초기 품질을 비교 검토하였다. 박피 방법별 감모율은 회전식 마찰형 박피기로 박피한 감자가 평균 7.9%, 고구마가 7.3%로 가장 우수하였다. 박피후 수분함량은 박피방법별로는 큰 차이가 없었으며 박피후 3시간까지 대체적으로 감소하였다. pH는 박피후 감자는 5.8-6.8, 고구마는 6.23-6.63이었으며 박피후 시간의 경과에 따라 다소 감소하였다. 경도는 일반과도를 이용한 수작업 박피가 우수하였다. 감자의 갈변도는 $100^{\circ}C$, 10% NaOH 90초 침지한 화학적 박피가 가장 컸으며, 고구마의 경우에서도 화학적 박피가 가장 큰 것으로 나타났다. 감자의 박피후 색차는 박피 전용도구를 이용한 수작업 박피, 회전식 칼날 삭피형 박피기와 회전식 브러시형 박피기를 이용한 박피가 변화량이 작았다. 고구마의 색차 변화는 회전식 칼날 삭피형 박피기를 이용한 박피가 가장 작았으며, 마찰형 박피기와 $100^{\circ}C$ 10% NaOH 처리 박피 고구마의 색차 변화가 상대적으로 모두 큰 것으로 나타났다.

• 대한치과기공학회지
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• 제32권3호
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• pp.195-207
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• 2010

Purpose: The purpose of this study was to observe the microstructural changes of surface in the specimens, performing the shear bond strength testing. The currently most used non-precious alloys are nickel-chromium based alloys with or without beryllium. However, their biocompatibility has been questioned concerning possible damages to the health of the patient and professionals involved in the fabrication of prosthesis caused by long exposure to Ni and Be. An option to nickel-chromium alloys is the cobalt-chromium alloy, an alternative that does not sacrifice the physical properties of the metal porcelain systems. Studies in the animals substantially show that the cobalt-chromium alloys are relatively well tolerated, being therefore more biocompatible than the nickel-chromium alloys. Methods: Non-addition Be to nickel-chromium based alloy(Bellabond plus) and cobalt-chromium alloy which has been widely used(Wirobond C) fused with ZEO light porcelain classified control group and cobalt-chromium alloy which is developing alloy of Alphadent company in Korea(Alphadent alloy) fused with ZEO light porcelain classified experimental group. The specimens of $4mm{\times}4mm{\times}0.5mm$ were prepared as-cast and as-opaque to cast body to analyze the mechanical characteristic change, the microstructure of alloy surface. The phase change was used to observe through XRD analysis and OM/SEM was used to observe the surface of specimens as-cast and as-opaque to cast body. Chemical formation of their elements was measured with EDS. Then hardness was measured with Micro Vicker's hardness tester. Shear bond strength test thirty specimens of $10mm{\times}10mm{\times}2mm$ was prepared, veneered, 3mm high and 3mm in diameter, over the alloy specimens. The shear bond strength test was performed in a universal testing machine(UTM) with a cross head speed of 0.5mm/min. Ultimate shear bond strength data were analyzed with one-way ANOVA and the Scheffe's test (P<0.05). Within the limits of this study, the following conclusions were drawn: The X-ray diffraction analysis results for the as-cast and as-opaque specimens showed that the major relative intensity of Bellabond plus alloy were changed smaller than Wirobond C and Alphadent Co-Cr based alloys. Results: Microstructural analysis results for the opaque specimens showed all the alloys increased carbides and precipitation(PPT). Alphadent Co-Cr based alloy showed the carbides of lamellar type. The Vickers hardness results for the opaque specimens showed Wirobond C and Alphadent Co-Cr based alloys were increaser than before ascast, but Bellabond plus alloy relatively decreased. The mean shear bond strengths (MPa) were: 33.11 for Wirobond C/ZEO light; 25.00 for Alphadent Co-Cr alloy/ZEO light; 18.02 for Bellabond plus/ZEO light. Conclusion: The mean shear bond strengths for Co-Cr and Ni-Cr based alloy were significantly different. But the all groups showed metal-metal oxide modes in shear bond strengths test at the interface.

• 대한치과기공학회지
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• 제30권2호
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• pp.39-45
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• 2008

Titanium and its alloys are widely used as dental implants materials because of their excellent mechanical properties. However, the alumina and zirconia ceramics are preferred to use as the substitute of Ti implants because there is a problems in esthetics and biocompatibility in Ti implant. The the glass infiltrated alumina ceramics are studied to increase the toughness and biocompatibility. The 45S5 and soda-lime glass powder was mixed with ethanol at ratio of 1:1 and brushed on the surface of alumina. Then it was heat treated in the electric furnace at $1400^{\circ}C$ from 30 min. to 5 hours. The glass powder was controlled from 200 to $350{\mu}m$ using ball milling. After heat treatment, the glass infiltrated specimen was tested in universal testing machine to measure the bending strength. The surface microstructure of each specimen was observed with SEM. The biocompatibility of 45S5 and soda-lime glass coated alumina was investigated using PBS at $36.5^{\circ}C$ incubator. The specimen was immersed in PBS for 3, 5, 7, 10 days. After that, the surface morphology was investigated with SEM. As the results of experiment, the 45S5 bioglass infiltrated alumina show the increase of bending strength according to the increasing of heat treatment time from 30 min. to 5 hours at $1400^{\circ}C$ Finally the 1370N bending strength of alumina increased to 1958N at 5 hours heat treatment, which shows 1.4 times higher. In contrast to this, the soda lime glass infiltrated alumina ceramics shows the convex curve according to heat treatment time. Thus it shows maximum bending strength of 1820N at 1 hour heat treatment of $1400^{\circ}C$ It gives 1.3 times higher. However, the bending strength of soda lime glass infiltrated alumina is decreasing with increasing heat treatment time after 1 hour. The precipitation on the surface of 45S5 glass infiltrated alumina was revealed as a sodium phosphate ($Na_{6}P_{6}O_{24}6H_{2}O$) and the amount of precipitation is increasing with increasing of immersion time in PBS. In contrast to this, there is no precipitation are observed on the surface of soda lime glass infiltrated alumina. This implies that 45S5 glass infiltrated alumina brings more biocompatible when it is implanted in human body.